In Danish:
Skaberlyst has amazing online courses in Danish. I have their old “Kom godt i gang med at sy”, “Lynlåse” and the current “Sy foer i dit tøj”. The courses are detailed, videobased and just great!
They also have the amazing pattern construction magazine Synoter, that I subscribe too with great enthusiasm! Every month there is a new either Magazine or theme, with lots of inspiration, techniques and stuff to learn.